Method of Evaluation of Deposits and Opening of Productive Formations

ABSTRACT

In a method of evaluation of deposits and opening of productive formations in recovery of oil or gas, a previously drilled well is located and investigated to determine at least one first zone which is not productive for oil or gas extraction and at least one second zone which is productive for oil or gas extraction; the at least one first zone which is not productive for oil or gas extraction is skipped, while hydroslotting is performed in the at least one second zone by making a plurality of slots and thereby producing unloaded regions so as to provide again a flow of oil or gas in the previously drilled well which was not in operation.

BACKGROUND OF THE INVENTION

The present invention relates to a mining industry and in particular to oil of gas exploration and extraction.

At the present time there are main oil and gas wells which were previously drilled, from which oil or gas were extracted and they are considered as depleted of oil or gas and thereby are no longer in operation. In view of scarcity of oil and gas, these wells can attract certain interest to make attempts to recover additional quantities of oil or gas therefrom. It is believed that some methods which have been used for this purpose can be further improved scarcity of oil and gas even these wells attract certain interested

SUMMARY OF THE INVENTION

Accordingly it is an object of the present invention to provide a new method of oil or gas recovery by evaluation of deposits and opening of productive formations in “old” oil and gas well, which is a further improvement of the existing methods.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method of evaluation of deposits and opening of productive formations in recovery of oil or gas, comprising the steps of locating a previously drilled well from which oil or gas was previously extracted and which is no longer in operation; investigating at least one formation in said previously drilled well from which oil or gas was previously extracted; determining by the investigation in said at least one formation at least one first zone which is not productive for oil or gas extraction; determining by the investigation in said at least one formation at least one second zone which is productive for oil or gas extraction; skipping in said at least one formation said at least one first zone which is not productive for oil or gas extraction; and hydroslotting in said at least one formation said at least one second zone by making a plurality of slots and thereby producing unloaded regions so as to provide again a flow of oil or gas in said previously drilled well which was not in operation.

In accordance with another feature of the present invention, said investigating of said at least one formation in said previously drilled well which is not in operation includes using a radioactive method of investigation via which said at least one first zone and said at least one second zone are determined in said at least one formation, or using a method of nuclear logging via which said at least one first zone and said at least one second zone are determined in said at least one formation, including transmission of signals to said at least one formation, receiving signals reflected signals reflected from said at least one formation and evaluating the reflected signals to determine said at least one first zone and at least one second zone.

A further feature of the inventive method includes performing said hydroslotting by asking said slots extending in a direction which is perpendicular to a direction of maximum stresses in near-well zone of said previously drilled well which is not in operation, or performing said hydrosolotting by making said slots extending in direction which is perpendicular to a directions of cracks in a near-well zone of said previously drilled well which is not in operation.

Still a further feature of the invention resides in that said determining includes evaluation of costs of extraction of oil or gas from said at least one first zone and at least one second zone, evaluation of quantities of oil or gas which can be excavated from said at least one first zone and said at least one second zone, considering said at least one zone as a not productive zone when the cost of the quantity of oil or gas extracted from it is lower than the cost of extraction of oil or gas from it, and considering said at least one second zone a productive zone when the cost of the quantity of oil or gas extracted from it is higher than the cost of extraction of oil or gas from it.

The novel features of the present invention are provided in the appended claims. The invention itself however will be best understood from the following description of the preferred embodiments, which is accompanied by the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings is a view illustrating a method of oil or gas recovery with evaluation of deposits and opening of productive formations, in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention a method is proposed for recovery of oil or gas from wells which were used previously and are not used anymore, with the utilization of evaluation of deposits and opening of productive formations in recovery of oil or gas from such wells. In the present invention a previously drilled well 1 from which oil or gas were previously extracted and which is no longer in operation.

At least one formation 2 in the previously drilled well 1 from which oil or gas was previously extracted, is then investigated. The carried out investigation determines in the at least one formation 2 at least one first zone 3 which is not productive for oil or gas extraction, and at least one second zone 4 which is productive for oil or gas extraction. Then in the at least one formation 2 the at least one first zone 3 which is not productive for oil or gas extraction is skipped. To the contrary, hydroslotting is performed in the at least one formation 2 in the at least one second zone 4 by making a plurality of slots and thereby producing unloaded regions so as to provide again a flow of oil or gas in the previously drilled well 1 which was not in operation.

It is to be understood that this can be done in several formation, and also that in a single formation several first zones and several second zones can be determined and treated in correspondence with the present invention.

The investigation of the at least one formation 2 in the previously drilled well 1 which is not in operation can include includes using a radioactive method of investigation via which the at least one first zone 3 and the at least one second zone 4 can be determined in the at least one formation 2. It is also possible to use for this purpose a method of nuclear logging via which the at least one first zone 3 and the at least one second zone 4 are determined in the at least one formation 2. In this case, the method of nuclear logging includes transmission of signals to the at least one formation 2, receiving signals reflected from the at least one formation 2, and evaluating the reflected signals to determine the

at least one first zone 3 and the at least one second zone 4.

In accordance with the inventive method, the hydroslotting can be performed by making the slots 5 extending in a direction which is perpendicular to a direction of maximum stresses in near-well zone of the previously drilled well 1 which is not in operation. Also the hydrosolotting can be performed by making the slots 5 extending in direction which is perpendicular to a directions of cracks in a near-well zone of the previously drilled well 1 which is not in operation.

In the method of the present invention, the zones determination process includes evaluation of costs of extraction of oil or gas from the at least one first zone 3 and at least one second zone 4, evaluation of quantities of oil or gas which can be excavated from the at least one first zone 3 and the at least one second zone 4, considering the at least one first zone 3 as a not productive zone when the cost of the quantity of oil or gas extracted from it is lower than the cost of extraction of oil or gas from it, and considering the at least one second zone 4 as a productive zone when the cost of the quantity of oil or gas extracted from it is higher than the cost of extraction of oil or gas from it.

In accordance with another new feature of the present invention, from the previously drilled well 1 which is not in operation, an additional inclined well 6 going to the at least one second zone 4 can be extended, and oil or gas can be extracted from the at least one second zone 4 via the additional inclined well 6.

The present invention is not limited to the details shown since various modifications and structural changes are possible without departing from the spirit of the invention. 

What is desired to be protected by Letters Patent is set forth in particular in the appended claims:
 1. A method of evaluation of deposits and opening of productive formations in recovery of oil or gas, comprising the steps of locating a previously drilled well from which oil or gas was previously extracted and which is no longer in operation; investigating at least one formation in said previously drilled well from which oil or gas was previously extracted; determining by the investigation in said at least one formation at least one first zone which is not productive for oil or gas extraction; determining by the investigation in said at least one formation at least one second zone which is productive for oil or gas extraction; skipping in said at least one formation said at least one first zone which is not productive for oil or gas extraction; and hydroslotting in said at least one formation said at least one second zone by making a plurality of slots and thereby producing unloaded regions so as to provide again a flow of oil or gas in said previously drilled well which was not in operation.
 2. A method as defined in claim 1, wherein said investigating of said at least one formation in said previously drilled well which is not in operation includes using a radioactive method of investigation via which said at least one first zone and said at least one second zone are determined in said at least one formation.
 3. A method as defined in claim 1, wherein said investigating of said at least one formation in said previously drilled well which is not in operation includes using a method of nuclear logging via which said at least one first zone and said at least one second zone are determined in said at least one formation.
 4. A method as defined in claim 3, further comprising providing in said method of nuclear logging transmission of signals to said at least one formation, receiving signals reflected from said at least one formation and evaluating the reflected signals to determine said at least one first zone and at least one second zone.
 5. A method as defined in claim 1, further comprising performing said hydroslotting by making said slots extending in a direction which is perpendicular to a direction of maximum stresses in near-well zone of said previously drilled well which is not in operation.
 6. A method as defined in claim 1, further comprising performing hydrosolotting by making said slots extending in direction which is perpendicular to a directions of cracks in a near-well zone of said previously drilled well which is not in operation.
 7. A method as defined in claim 1, wherein said determining includes evaluation of costs of extraction of oil or gas from said at least one first zone and at least one second zone, evaluation of quantities of oil or gas which can be excavated from said at least one first zone and said at least one second zone, considering said at least one first zone as a not productive zone when the cost of the quantity of oil or gas extracted from it is lower than the cost of extraction of oil or gas from it, and considering said at least one second zone a productive zone when the cost of the quantity of oil or gas extracted from it is higher than the cost of extraction of oil or gas from it.
 8. A method as defined in claim 1, further comprising extending from said previously drilled well which is not in operation an additional inclined well going to said at least one second zone, and extracting oil or gas from said at least one second zone via said additional inclined well. 